Dredge



Nov. 23, 1965 c. P. KAUFMANN ETAL 3,218,739

DREDGE Filed May 13, 1965 3 Sheets-Sheet l INVENTORS CAPL wu/ MAA/M g 6064.? you 504/744,?

BY ,/chzx MWEA/AA FAPp/A/G TOA/ A770 A/EKS 23, 1965 c. P. KAUFMANN ETAL 3,218,739

DREDGE Filed May 13, 1963 3 Sheets-Sheet 2 INVENTORS NOV. 23, 1965 c. P. KAUFMANN ETAL 3,218,739

DREDGE 3 Sheets-Sheet 5 Filed May 13, 1965 United States Patent 3,218,739 DREDGE Carl P. Kaufmann, Baltimore, and Edgar Von Bolhar, Severna Park, Md., assignors to Ellicott Machine Corp., Baltimore, Md, a corporation of Maryland Filed May 13, 1963, Ser. No. 279,785 13 Claims. (Cl. 3756) This invention relates generally to hydraulic dredges and more particularly to an improved dredging apparatus suitable for operation at substantial depths below the surface of a body of water.

In our co-pending application, Serial No. 231,203, filed October 17, 1962, now Patent No. 3,171,219 issued March 2, 1965, a dredging apparatus is disclosed which includes a Watertight submersible capsule on which is mounted a cutter and which houses a hydraulic pump, motors to drive the cutter and pump, and controls therefor. This Watertight capsule is supported at the bottom of a body of water and can operate at very substantial depth to efliciently dredge material. The present invention includes a watertight capsule substantially as disclosed in the prior application cited above, but provides novel and improved structure for positioning and controlling the capsule. A work platform is provided which is supported by adjustable caissons extending to the bottom of the body of water. In the particular embodiment illustrated a compound work platform is shown which is capable of moving or walking along the botom as the dredging progresses and as particularly suited for dredging for tunnels to produce a tunnel receiving ditch in the bottom of the body of water and for mining and the like. The watertight capsule is supported when it operates by a structure anchored to the bottom so that it is not necessary to absorb the reactive forces of dredging through an elongated support extending from the Work platform. The various structural elements are arranged so that complete control of the dredging capsule is maintained at all times and so that the watertight capsule can be lifted to a position above the surface of the water for service and the like.

It is an important object of this invention to provide a novel and improved hydraulic dredging structure suit able for dredging at substantial depths below the surface of the body of water.

It is another important object of this invention to provide a novel and improved dredge combining a dredge capsule or watertight hull in which the dredging apparatus is mounted and a support for the dredge capsule securely anchored to the bottom and provided with means to control the movement of the dredging capsule from a work platform located above the water.

It is another important object of this invention to provide a novel and improved hydraulic dredge combining a dredging capsule housing the dredging machinery and a work platform supported on caissons resting on the bottom wherein the dredging capsule is connected to the caissons by a saddle supported adjacent to the lower end of the caissons and means are provided to control the positioning and movement of the capsule with respect to the saddle.

It is another important object of this invention to provide a novel and improved hydraulic dredge as set forth in the last preceding object wherein the saddle can be moved axially with respect to the supporting caisson so that the dredge capsule can be raised to a position above the water surface or lowered to a position at the bottom.

Further objects and advantages will appear from the following description and drawings wherein:

FIGURE 1 is a perspective view, with some parts broken away for purposes of illustration, of a hydraulic 3,218,739 Patented Nov. 23, 1965 dredge incorporating this invention illustrating the support structure and operation of the dredge;

FIGURE 2 is a side elevation illustrating the support structure and its operation in controlling the dredge capsule;

FIGURE 3 is an end view similar to FIGURE 2 further illustrating the structure of a dredge incorporating this invention and the operation of the dredge to excavate a ditch in the bottom;

FIGURE 4 is a plan view of the dredge incorporating this invention; and,

FIGURE 5 is an enlarged fragmentary section of a pneumatic gripper used to reduce clearance between the associated parts to prevent destructive vibrations.

A rectangular upper work platform 10 is supported on six outer caissons 11 with one located at each corner and one in the middle of each side. The caissons are vertically movable with respect to the platform by means of power driven hoists (not shown). A rectangular work platform 12 is connected to the upper platform 10 for relative longitudinal movement on guide rails 13. The upper platform 10 is formed with depending side sections 14 which extend down to a position substantially aligned with the lower side of the lower platform 12 and support the rails 13. The lower platform 12 is provided with a longitudinally extending guideway 16 on each side which embraces the associated rail 13. Drive means (not shown) are connected between the two work platforms 10 and 12 to produce the relative longitudinal movement therebetween.

Six inner caissons 17 extend through the lower work platform with one mounted in each corner thereof, and one centrally located on each longitudinal side. The inner caissons 17 are supported on bearings on the lower work platforms for vertical movement with respect thereto. Here again, power-driven hoist means are provided (not shown) to raise and lower the caissons 17 relative to the lower platform 12. The upper work platform is provided with an elongated opening 18 associated with each inner caisson 17 through which the upper end of the inner caissons extend. The openings 18 are proportioned so that they provide clearance throughout the entire length of relative movement between the upper and lower work platforms 10 and 12. In the illustrated structure the lower platform is movable relative to the upper platform through a distance of about fifty feet. Therefore, the openings 18 have a length greater than fifty feet so that clearance is provided in all positions of the two platforms.

The two work platforms 10 and 12 are watertight and provide sufficient buoyancy so that the entire structure will float and can be towed when the caissons 11 and 17 are raised. Once the dredge is located at the dredging location the caissons are lowered until they engage the bottom 19. Additional downward movement of the caissons, with respect to the platforms, raises the platforms to the position illustrated well above the surface 21 of the Water.

The operation of the separate sets of caissons and the two work platforms permits the platforms to be walked along the bottom 19 as the work progresses. This walking or movement is accomplished by raising the inner caissons 17 clear of the bottom 19 while supporting the entire assembly on the outer caissons 11. The lower work platform 12 is then moved forward, with respect to the upper work platform 10, to its forward extreme position. The inner caissons 17 are then lowered to support the assembly and the outer caissons 11 raised clear of the bottom. The upper work platform 10 is then moved forward with respect to the lower work platform after which the outer caissons are lowered into engagement with the bottom. This process can be repeated so that the entire structure can be moved forward about fifty feet in each step, allowing the dredging to be carried forward any required distance through repeated Walking operations. Because the work platforms are supported on the bottom 19 at all times, accurate control of the movement of the structure is achieved. The structure of the work platforms and caissons per se forms no part of this invention except in combination with the dredge operation and support.

The dredging is accomplished by a dredging capsule 22 having a rotary cutter 23 mounted at the end of an elongated extension 24. The capsule provides a watertight hull in which a motor for driving the cutter 23 is located. Also enclosed within the hull is a motor-driven pump 25 having an inlet pipe 26 open at a position adjacent to the lower side of the cutter 23. Power for the capsule is generated by suitable motor generator units located on the work platform. Preferably the power is supplied to the capsule through a cable (not shown) extending from a large diameter take-up sheave on the upper platform 10. For a detailed description of the structure of the capsule 22 and the machinery arrangement within the capsule reference should be made to our copending application cited above.

T provide lateral support for the capsule 22 a saddle 27, best illustrated in FIGURE 1, is mounted on four of the inner caissons 17. The saddle 27 includes a forward bridge member 28 through which the forward two of the inner caissons extend. A hearing is provided between the forward bridge member 28 and the associated caissons 17 so that relative vertical movement may be provided between the bridge member 28 and the associated caissons. A similar rearward bridge member 29 is slidably mounted on the rearward two inner caissons 17. Extending between the two bridge members 28 and 29 are a pair of parallel support beams 31 completing the saddle structure. Four hoists 32 are mounted adjacent to the lower side of the lower work platform 12 and are connected by wire rope 33 to the saddle 27 with two ropes 33 connected to each bridge member 28 and 29. Operation of the hoist 32 permits the raising and lowering of the saddle 27 with respect to the work platforms, causing the saddle to slide up or down along the inner caissons 17 Mounted for axial movement on the beams 31 is a yoke 34. The axial movement of the yoke 34 along the beams 31 is controlled by any suitable power means. In the illustrated embodiment hydraulic piston and cylinder actuators are used. The cylinders 36 are mounted on the bridge member 29, and the pistons 37 are connected to the yoke 34. Preferably, two cylinders are provided symmetrically connected with respect to the yoke. The cylinders 36 are both double acting so they operate to move the yoke 34 in both directions with respect to the saddle 27 between the full line retracted position, of FIG- URE 2, and the phantom line extended position.

A parallelogram linkage is connected between the yoke 34 and an upper housing 38 on which the dredging capsule 22 is mounted. This linkage includes four rigid beams 39 each pivoted at one end on the yoke 34 at a pivot 41 and at their opposite end on the upper housing 38 at a pivot 42. The pivots 41 and 42 are all parallel and are spaced so that the beams 39-forrn parallelograms, best illustrated in FIGURE 2.

A pair of hoists 43 are mounted on a mast 44 carried by the lower work platform 12 and are connected by wire rope 46 to pulleys 47 mounted on the upper end of the upper housing 38. Therefore, the hoist 43 can be operated to raise and lower the upper housing 38 and in turn the capsule 22. When the upper housing 38 is raised with respect to the saddle 27 the beams 39 pivot about their respective pivots 41 and 42, thereby controlling the horizontal position of the upper housing 38 and in turn the capsule 22. However, the hoists 43 carry the weight of the capsule and upper housing. The upper platform is formed with a central opening through which the mast 44 extends with clearance.

The discharge of the pump located within the capsule 22 is connected to a discharge hose 48 which extends upwardly to a pivot mount 49 on the upper work platform 10. The discharge hose 48 is preferably formed of reinforced rubber material which provides a limited amount of flexibility so that the capsule 22 can be moved with respect to the work platforms without damaging the hose. However, since the hose has a relatively large diameter it is quite heavy and cannot bend sharply. Therefore a support is provided including a cable clamp 51 mounted approximately at the middle of the hose 48 and connected to one end of a wire rope 52. The rope 52 extends over pulley 53 and 54 and is connected at its other end to a counterbalance weight 56 located within one of the caissons 17.

The pulley 53 is mounted at the upper end of a mast extension 57 and pulley 54 is mounted on the upper end of the caisson 17 in which the counterweight 56 is positioned. This structure provides a substantially constant tension in the rope 52 regardless of the position of the hose 48. When it is desired to raise the capsule 22 above the surface of the water for maintenance or repairs, the winches 32 and 43 are operated to raise the saddle 27 and capsule 22 to the upper phantom position, illustrated in FIGURES 2 and 3. At this time the capsule 22 and saddle are above the surface 21. As the capsule is moved upward the counterweight 56 raises the rope to the upper phantom position, illustrated in FIGURE 2, so that a smooth large radius bend is provided preventing damage to the hose 48. A curved grizzly 58 is mounted on the upper work platform 10 adjacent to the discharge of the hose 48 and is proportioned so that it will properly function in all positions of the hose. The lower work platform is also formed with a central opening into which the upper housing moves when the capsule is raised.

The capsule 22 is journaled on the upper housing 38 for rotation relative thereto about a vertical axis 60 and is provided with a bull gear 59 driven by rotary motors 61 symmetrically positioned around the upper housing 38. The motors 61 may be of any suitable submersible type, however, electric motors are used in the illustrated embodiment. These motors operate to swing the capsule 22 around the axis'60 so that the dredge can operate to excavate a ditch having a width up to about twice the horizontal distance from the axis 60 to the cutter 23.

The operation of the cutter 23 during dredging tends to produce a substantial amount of vibration. Therefore, gripping or locking devices 71 are used to eliminate clearance in the bearings of the saddle 27 on the caissons 17 and in the bearing of the yoke 34 on the beams 31. FIGURE 5 is a section schematically illustrating the structure of one form of such locking device. It should be understood that other forms such as wedge grips might be used.

The beam 29 is provided with a clearance bearing surface 72 through which the caisson 17 extends. Spaced annular recesses 73 are provided to receive inflatable tubes 74 formed of rubber-like material. The tubes are connected by suitable pressure lines (not shown) to a control panel on one of the work platforms so that they may be exhausted for free movement of the saddle and yoke or pressurized during dredging to remove the clearance and eliminate possible chattering.

In operation the saddle 27 and the caissons 17 are lowered until the caissons rest on the bottom and the saddle is adjacent to the bottom 19. During this movement the hoist 43 maintains the capsule 22 above the bottom 19. Preferably the hoists and drives are operated so that the saddle is adjacent to the lower end of the caissons 17 when they are lowered so that the saddle will maintain the proper alignment of such lower ends of the caissons 17. The inner caissons are provided with collars 30 which prevent accidental raising of the caissons out of the bridge members 28 and 29. The dredging commences with lowering the cutter 23 into the bottom 19 while swinging the capsule around the axis 60 with the motors 61 and moving the yoke 34 as required with pressure supplied to the cylinders 36. When dredging a ditch 62 the dredging is continued until the pistons 37 extend the yoke forward to the maximum position of their stroke, as illustrated in FIGURE 2, this would cause the dredge to excavate the ditch 62 to a position illustrated by the dotted line 63. It should be understood that during this operation the hoists 43 and motors 61 operate to swing the cutter back and forth and up and down so that full removal of bottom material is provided.

When the excavation is completed to the maximum stroke of the piston 37, the yoke is pulled back to the full line position of FIGURE 2 so that the cutter 23 is back from the face of the excavation 63. The inner caissons 17 are then lifted clear of the bottom 19 and the lower work platformjs moved forward, relative to the upper platform 10, bringing the saddle 27 and in turn the capsule 22 forward to the face of the excavation 63. The entire structure is supported on the outer caissons 11 during this operation. The inner caissons 17 are then lowered into engagement with the bottom 19 and the outer caissons 11 lifted clear. At this time the upper platform is moved forward with respect to the lower platform 12 while the structure is supported on the inner caissons 17. The dredging may, if desired, be continued during the movement of the upper platform to the forward position. Once the upper platform 10 is in the forward position the caissons 11 are again lowcred into engagement with the bottom. This process can be repeated and dredging continued for any desired distance.

In some instances it may be desired to move the capsule 22 horizontally Without using the cylinders 36. When this is desired the capsule is lowered below the saddle until the beams 39 are almost vertical. The saddle and capsule are then simultaneously lowered to required dredging depth. The capsule is then held at this depth and the saddle lowered, causing the beams to move to a position more nearly approaching horizontal thereby moving the capsule forward. By utilizing this method of operation in combination with the cylinders 36 it is possible to make a out having a length which exceeds the stroke of the cylinders without moving the platforms.

The structure is arranged so that the lateral reactions of dredging are transmitted through the beams 39 directly to the saddle 27 and therefrom to the lower end of the inner caissons 17 adjacent to the bottom 19. Since the path of the reactive forces is relatively short and is absorbed by the firm anchoring of the caissons 17 and the bottom 19, a substantially rigid system is provided and extremely accurate control of the position of the capsule 22 is maintained. Also, the fact that the movement of the capsule in all three directions is positively controlled provides a structure where accuracy of dredging may be insured. The parallelogram support of the beams 39 maintains the capsule upright and the pivoted mounting of the beams minimizes the bending movements applied thereto. Also, the beams converge toward the upper housing 38, as illustrated in FIGURE 3, so that lateral dredging forces do not produce excessive bending loads in the beams.

Because the pump 25 is located adjacent to the bottom and there is a relatively short distance between the inlet of the pump and the inlet of the pipe 26 an efficient dredging operation can be performed at very great depth. It should be understood that all of the dredging operations can be controlled from the work platforms so that it is not necessary for operating personnel to be stationed within the capsule 22.

Although a preferred embodiment of this invention is illustrated, it is to be understood that various modifications and rearrangements of parts may be resorted to without departing from the scope of the invention as defined in the following claims.

What is claimed is:

1. A hydraulic dredge for excavating the bottom under a body of water comprising a work platform, a plurality of caissons resting on the bottom supporting said plat form above the surface of the water, a submerged saddle laterally supported on at least some of said caissons adjacent to said bottom, a submerged dredging capsule including a cutter and a pump, and support means operatively connecting said saddle and capsule controlling the horizontal position of said capsule with respect to said saddle, said support means including a horizontal drive operable to move said capsule horizontally with respect to said saddle.

2. A hydraulic dredge for excavating the bottom under a body of water comprising a work platform, a plurality of caissons adapted to rest on the bottom supporting said platform above the surface of the water, a submergible saddle laterally supported on at least some of said caissons adjacent to said bottom, a submergible dredging capsule including a cutter and a pump, and support means operatively connecting said saddle and capsule controlling the horizontal position of said capsule with respect to said saddle, said support means including a rotary drive operable to rotate said capsule relative to said saddle about a vertical axis and a horizontal drive operable to move said capsule horizontally with respect to said saddle.

3. A hydraulic dredge for excavating the bottom under a body of water comprising a work platform, a plurality of caissons resting on the bottom supporting said platform above the surface of the water, a submerged saddle laterally supported on at least some of said caissons adjacent to said bottom, a submerged dredging capsule including a cutter and a pump, support means operatively connecting said saddle and capsule controlling the horizontal position of said capsule with respect to said saddle, said support means including a rotary drive operable to rotate said capsule relative to said saddle about a vertical axis and a horizontal drive operable to move said capsule horizontally with respect to said saddle, and hoist means operably connected to said capsule controlling the vertical position of said capsule in respect to said bottom.

4. A hydraulic dredge for excavating the bottom under a body of water comprising a work platform, a plurality of caissons resting on the bottom supporting said platform above the surface of the Water, a submerged saddle laterally supported on at least some of said caissons adjacent to said bottom, .a submerged dredging capsule including a cutter and a pump, support means operatively connecting said saddle and capsule controlling the horizontal position of said capsule with respect to said saddle, said support means including a rotary drive operable to rotate said capsule relative to said saddle about a vertical axis and a horizontal drive operable to move said capsule horizontally with respect to said saddle, and rope hoist means operably connected between said platform and capsule controlling the vertical position of said capsule in respect to said bottom.

5. A hydraulic dredge for excavating the bottom under a body of water comprising a submersible capsule including a cutter and a pump operable to excavate said bottom, submerged saddle means supported adjacent said bottom and anchored against horizontal movement relative thereto, support means operatively connected between said saddle and capsule controlling the horizontal position of said capsule with respect to said saddle, said support means including the rotary drive operable to rotate said capsule relative to said saddle about an axis and a horizontal drive operable to move said capsule horizontally relative to said saddle.

6. A hydraulic dredge for excavating the bottom under a body of water comprising a submersible capsule in cluding a cutter and a pump operable to excavate said bottom, four columns anchored on said bottom, submerged saddle means supported on said columns adjacent said bottom, a yoke movable on said saddle, power means controlling the movement of said yoke relative to said saddle, and rigid beams connected between said yoke and capsule absorbing the reactive forces of dredgmg.

7. A hydraulic dredge for excavating the bottom under a body of water comprising a submersible capsule including a cutter and a pump operable to excavate said bottom, submerged saddle means supported adjacent said bottom and fixed against movement relative thereto, a yoke mounted on said saddle for movement relative thereo, power means controlling such movement of said yoke, and beams connected between said yoke and capsule absorbing reactive forces of dredging.

8. A hydraulic dredge for excavating the bottom under a body of Water comprising submergible saddle means adapted to be positioned adjacent to said bottom and fixed against movement relative thereto, a submersible dredging capsule including a power-driven cutter, a yoke mounted on said saddle for linear movement relative thereto between extended and retracted positions, motor means connected between said yoke and saddle operable to move said yoke between said extended and retracted positions, an upper housing on said capsule connected to said capsule and permitting movement thereof about a vertical axis, power means connected between said upper housing and capsule operable to rotate said capsule about said axis, and a plurality of beams connected to said yoke and upper housing preventlng rotation of said upper housing about said axis and transmitting reactive forces of dredging to said yoke.

9. A hydraulic dredge for excavating the bottom under a body of water comprising submergible saddle means adapted to be positioned adjacent to said bottom and fixed against movement relative thereto, a submersible dredging capsule including a power-driven cutter, a yoke mounted on said saddle for linear movement relative thereto between extended and retracted positions, motor means connected between said yoke and saddle operable to move said yoke between said extended and retracted poistions, an upper housing on said capsule connected to said capsule and permitting relative movement therebetween about a vertical axis, power means connected between said upper housing and capsule operable to rotate said capsule about said axis, and a plurality of beams pivotally connected to said yoke and upper housing and cooperating therewith to form a parallelogram linkage permitting vertical movement of said upper housing, preventing rotation of said upper housing about said axis and transmitting reactive forces of dredging to said yoke, and power means connected to raise and lower said upper housing with respect to said bottom.

10. A'hydraulic dredge for excavating the bottom under a body of water comprising a pair of work platforms horizontally movable relative to each other, a plurality of first caissons connected to one of said work latforms operable to rest on said bottom and support said work platforms above the surface of said water, a plurality of second caissons mounted on the other of said work platforms operable to rest on said bottom and support said work platforms above said surface of said water, a submersible dredging capsule including a cutter operable to excavate said bottom, a saddle on said first caissons adapted to be positioned adjacent to said bottom, support means operatively connected between said saddle and capsule operable to move said capsule horizontally with respect to said saddle, the mounting of said caissons on said work platforms permitting vertical movement of said caissons relative to said work platforms, and power means operable to produced relative horizontal movement between said platforms and relative vertical movement between said caissons and platforms whereby said platforms may be walked along said bottom by alternately supporting said work platforms on said first and said second caissons.

11. A hydraulic dredge for excavating the bottom under a body of water comprising a pair of work platforms horizontally movable relative to each other, a plurality of first caissons connected to one of said work platforms operable to rest on said bottom and support said work platforms above the surface of said water, a plurality of second caissons mounted on the other of said work platforms operable to rest on said bottom and support said work platforms above said surface of said water, a submersible dredging capsule including a cutter operable to excavate said bottom, a saddle on said first caissons supported from said one platform adjacent to said bottom, support means operatively connected between said saddle and capsule operable to move said capsule horizontally with respect to said saddle, hoist means connected between said work platforms and said capsule operable to vertically position said capsule with respect to said bottom, the mounting of said caissons on said work platforms permitting vertical movement of said caissons relative to said work platforms, and power means operable to produce relative horizontal movement between said platforms and relative vertical movement between said caissons and platforms whereby said platforms may be walked along said bottom by alternately supporting said work platforms on said first and second caissons.

12. A hydraulic dredge for excavating the bottom under a body of water comprising a pair of work platforms horizontally movable relative to each other, a plurality of first caissons connected to one of said work platforms operable to rest on said bottom and support said work platforms above the surface of said water, a plurality of second caissons mounted on the other of said work platforms operable to rest on said bottom and support said Work platforms above said surface of said water, a submersible dredging capsule including a cutter and a pump operable to excavate said bottom, a saddle on said first caissons adapted to be positioned adjacent to said bottom, a yoke movable horizontally on said saddle, beams connecting said yoke and capsule absorbing reactive forces of dredging, means operable to rotate said capsule about a vertical axis, and hoist means connected between said work platforms and said capsule operable to vertically position said capsule with respect to said bottom, the mounting of said caissons on said work platforms permitting vertical movement of said caissons relative to said work platforms, and power means operable to produce relative horizontal movement between said platforms and relative vertical movement between said caissons and platforms whereby said platforms may be walked along said bottom by alternately supporting said work platforms on said first and second caissons.

13. A hydraulic dredge for excavating the bottom under a body of water comprising a work platform, a plurality of caissons connected to said work platform operable to rest on said bottom and support said work platform above the surface of said water, a submersible dredging capsule including a cutter and a pump, a discharge pipe connected to said pump and extending to said platform, support means operatively connected to said capsule and operable to move said capsule vertically with respect to said platform, a rope connected to a mid-section of said pipe and to a weight located in one of said caissons whereby the mid-section of said pipe is lifted into a smooth bend when said capsule is raised relative to said platform.

(References on following page) 9 I 10 References Cited by the Examiner FOREIGN PATENTS UNITED STATES PATENTS 958,839 3/1950 France.

873,481 7/1961 Great Bntain. 516,032 3/1894 Symonds 175 9 B STO 626,491 6/1899 Ford 37-67 5 3g i g 'fi HI 2,830,788 4/1958 Bentley 6146.5 B M M Examiners. 

7. A HYDRAULIC DREDGE FOR EXCAVATING THE BOTTOM UNDER A BODY OF WATER COMPRISING A SUBMERSIBLE CAPSULE INCLUDING A CUTTER AND A PUMP OPERABLE TO EXCAVATE SAID BOTTOM, SUBMERGED SADDLE MEANS SUPPORTED ADJACENT SAID BOTTOM AND FIXED AGAINST MOVEMENT RELATIVE THERETO, A YOKE MOUNTED ON SAID SADDLE FOR MOVEMENT RELATIVE THEREO, POWER MEANS CONTROLLING SUCH MOVEMENT OF SAID YOKE, AND BEAMS CONNECTED BETWEEN SAID YOKE AND CAPSULE ABSORBING REACTIVE FORCES OF DREDGING. 